Method and system for operating multiple dependent networks

ABSTRACT

A device and method for ultra wide band transmission, the method includes: (a) allowing a first group of ultra wide band devices to exchange information using a first frequency hopping sequence; and (b) allowing at least one certain device that is responsive to at least one transmission of information from a device of the first group to exchange information using the first frequency hopping sequence during at least one time period and allowing devices that belong to the second group to exchange information using a second frequency hopping sequence during at least one other time period.

RELATED APPLICATIONS

The present patent application is a continuation application ofInternational Application No. PCT/IL05/000021 filed Jan. 96, 2005, whichclaims priority benefit from U.S. Provisional Application No. 60/535,436filed Jan. 8, 2004 and U.S. Provisional Application No. 60/535,621 filedJan. 8, 2004, the contents of which are incorporated herein byreference.

This application is related to the following applications:

-   1. METHOD AND DEVICES FOR MULTICASTING INFORMATION OVER A NETWORK    THAT APPLIED A DISTRIBUTED MEDIA ACCESS CONTROL SCHEME, application    Ser. No. ______, filed Jan. 25, 2005.-   2. METHODS AND DEVICES FOR EXPANDING THE RANGE OF A NETWORK,    application Ser. No. ______, filed Jan. 25, 2005.-   3. A DEVICE AND METHOD FOR MAPPING INFORMATION STREAMS TO MAC LAYER    QUEUES, application Ser. No. ______, filed Jan. 25, 2005.-   4. ULTRA WIDE BAND WIRELESS MEDIUM ACCESS CONTROL METHOD AND A    DEVICE FOR APPLYING AN ULTRA WIDE BAND WIRELESS MEDIUM ACCESS    CONTROL SCHEME, application Ser. No. ______, filed Jan. 25, 2005.-   5. METHOD AND DEVICE FOR TRANSMISSION AND RECEPTION OVER A    DISTRIBUTED MEDIA ACCESS CONTROL NETWORK, application Ser. No.,    filed Jan. 25, 2005.

FIELD OF THE INVENTION

The invention relates to methods and device for operating multipledependent networks and especially multiple adjacent ultra wide bandnetworks.

BACKGROUND OF THE INVENTION

Recent developments in telecommunication and semiconductor technologiesfacilitate the transfer of growing amounts of information over wirelessnetworks.

The demand for short to medium range, high speed connectivity formultiple digital devices in a local environment continues to risesharply. For example, many workplaces and households today have manydigital computing or entertainment devices such as desktop and laptopcomputers, television sets and other audio and video devices, DVDplayers, cameras, camcorders, projectors, handhelds, and others.Multiple computers and television sets, for instance, have become commonin American households. In addition, the need for high speedconnectivity with respect to such devices is becoming more and moreimportant. These trends will inevitably increase even in the nearfuture.

As the demand for high speed connectivity increases along with thenumber of digital devices in typical households and workplaces, thedemand for wireless connectivity naturally grows commensurately.High-speed wiring running to many devices can be expensive, awkward,impractical and inconvenient. High speed wireless connectivity, on theother hand, offers many practical and aesthetic advantages, whichaccounts the great and increasing demand for it. Ideally, wirelessconnectivity in a local environment should provide high reliability, lowcost, low interference caused by physical barriers such as walls or byco-existing wireless signals, security, and high speed data transfer formultiple digital devices. Existing narrowband wireless connectivitytechniques do not provide such a solution, having problems such as highcost, unsatisfactory data transfer rates, unsatisfactory freedom fromsignal and obstacle related interference, unsatisfactory security, andother shortcomings. In fact, the state of the art does not provide asufficiently satisfactory solution for providing high speed wirelessconnectivity for multiple digital devices in a local environment.

The state of the art in wireless connectivity generally includesutilization of spread spectrum systems for various applications. Spreadspectrum techniques, which spread a signal over a broad range offrequencies, are known to provide high resistance against signalblocking, or “jamming,” high security or resistance against“eavesdropping, ” and high interference resistance. Spread Spectrumtechniques have been used in systems in which high security and freedomfrom tampering is required. Additionally, Code Division Multiple Access(CDMA), a spread spectrum, packet-based technique, is used in somecellular phone systems, providing increased capacity in part by allowingmultiple simultaneous conversation signals to share the same frequenciesat the same time.

Known spread spectrum and modulation techniques, including CDMAtechniques, direct sequence spread spectrum (DSSS) techniques, timehopping spread spectrum (THSS) techniques, and pulse position modulation(PPM) techniques, do not satisfactorily provide wireless connectivity ina local environment, including high reliability, low cost, lowinterference, security, and high speed data transfer for multipledigital devices. In addition, known UWB transmission and communicationmethods and systems lack satisfactory quality in areas that can includeflexibility, adaptivity and adaptive trade-off capabilities in areassuch as power usage, range, and transfer rates, and low costimplementation.

A number of U.S. and non-U.S. patents and patent applications discussspread spectrum or UWB related systems for various uses, but arenonetheless in accordance with the above described state of the art. TheU.S. and non-U.S. patents and patent applications discussed below arehereby incorporated herein by reference in their entirety.

There are several Japanese patents and applications in some of theseareas. Japanese patent application JP 11284599, filed on Mar. 31, 1998and published on Oct. 15, 1999, discusses spread spectrum CDMA mobilecommunications. Japanese patent application JP 11313005, filed on Apr.27, 1998 and published on Nov. 9, 1999, discusses a system for rapidcarrier synchronization in spread spectrum communication using anintermittently operative signal demodulation circuit. Japanese patentapplication JP 11027180, filed on Jul. 2, 1997 and published on Jan. 29,1999, and counterpart European application EP 0889600 discuss areceiving apparatus for use in a mobile communications system, andparticularly for use in spread spectrum Code Division Multiple Accesscommunications between a base station and a mobile station. Japanesepatent application JP 21378533, filed on Nov. 18, 1988 and published onMay 25, 1990, discusses a transmitter for spread spectrum communication.

A number of U.S. patents and published applications discuss spreadspectrum or UWB in various contexts. U.S. Pat. No. 6,026,125, issuedFeb. 15, 2000 to Larrick, Jr. et al., relates to utilization of acarrier-controlled pulsed UWB signal having a controlled centerfrequency and an adjustable bandwidth. U.S. Pat. No. 6,351,652, issuedFeb. 6, 2002 to Finn et al., discusses impulse UWB communication. U.S.Pat. No. 6,031,862, issued Feb. 29, 2000 to Fullerton et al., andrelated patents including U.S. Pat. Nos. 5,677,927, 5,960,031,5,963,581, and 5,995,534, discuss a UWB communications system in whichimpulse derived signals are multiplied by a template signal, integrated,and then demodulated, to increase the usability if signals which wouldotherwise be obscured by noise. U.S. Pat. No. 6,075,807, issued Jun. 13,2000 to Warren et al., relates to a spread spectrum digital matchedfilter. U.S. Pat. No. 5,177,767, issued Jan. 5, 1993 to Kato, discussesa “structurally simple” wireless spread spectrum transmitting orreceiving apparatus which is described as eliminating the need for codesynchronization. U.S. Pat. No. 6,002,707, issued Dec. 14, 1999 to Thue,relates to radar system using a wide frequency spectrum signal for radartransmission to eliminate the need for very high energy narrow pulsetransmitter and receiver systems. U.S. Pat. No. 5,347,537, issued Jun.21, 1994 to Mori, et al., and related patents including U.S. Pat. Nos.5,323,419 and 5,218,620, discuss a direct sequence spread spectrumtransmitter and receiver system. U.S. Pat. No. 5,206,881, issued Apr.27, 1993, discusses a spread spectrum communication system attempting touse rapid synchronization of pseudo-noise code signals with data packetsignals.

A number of published PCT international applications also discuss spreadspectrum or UWB in various contexts. PCT international application,publication number WO 01/39451 published on May 31, 2001, discusses awaveform adaptive transmitter for use in radar or communicationsapplications. PCT international application, publication number WO01/93441, published on Dec. 6, 2001, discusses a UWB high-speed digitalcommunication system using wavelets or impulses. PCT internationalapplication, publication number WO 01/99300, published on Dec. 27, 2001,discusses wireless communications using UWB signaling. PCT internationalapplication, publication number WO 01/11814, published on Feb. 15, 2001,discusses a transmission method for broadband wired or wirelesstransmission of information using spread spectrum technology.

Short-range ultra wide band wireless networks are being developed inorder to allow wireless transmission of vast amounts of informationbetween various devices. U.S. patent application 2003/0063597 of Suzuki,titled “Wireless transmission system, wireless transmission method,wireless reception method, transmitting apparatus and receivingapparatus”, which is incorporated herein by reference, describedwireless networks that each includes a base station. U.S. patentapplication 2004/0170217 of Ho titled “Wireless personal area networkswith rotation of frequency hopping sequences” describes a multiplepiconets (personal network) environment in which each piconets iscontrolled by a piconets coordinator. Non-related and non-synchronizedpiconets use rotating frequency hopping sequences in order to avoidinterferences.

Some of short-range ultra wide band wireless networks are characterizedby a distributed architecture in which devices exchange informationwithout being controlled by a central host or a base station.

FIG. 1 is a schematic illustration of two ultra wide band wirelessnetworks (also referred to as personal access networks) 10 and 20, eachincluding multiple devices that wirelessly communicate with each other.First network 10 includes first till third devices A-C 11-13 and thesecond network 20 includes forth till sixth devices D-F 24-26.

FIG. 2 illustrates a typical TDMA frame 30. TDMA frame 30 includesmultiple time-slots, such as beacon slots 14 and media access slots. Themedia access slots include distributed reservation protocol (DRP) slots36 and prioritized contention access (PCA) slots 38. PCA slots are alsoreferred to as PCA periods. DRP slots are also referred to as DRPperiods.

The beacon slots are used to synchronize devices to the TDMA frame 30. Atypical beacon frame includes information that identifies thetransmitting device. It also may include timing informationrepresentative of the start time of the TDMA frame 30.

The DRP slots 36 are coordinated between devices that belong to the samenetwork and allow devices to reserve these slots in advance. During thePCA slots 38 devices that belong to the network compete for access basedupon their transmission priority. It is noted that the allocation ofmedia access time slots is dynamic and can change from one TDMA frame toanother.

Typically, transmissions from devices during PCA slots are assigned byapplying a carrier sense multiple access with collision avoidance(CSMA/CA) scheme If a device requests to transmit over a wireless mediumit has to check if the wireless medium is idle. If the wireless mediumis idle, the device has to wait a random backoff period. This randombackoff time is selected from a contention window that has a length thatis related to the priority of the device. For higher-priority devicesthe contention window is shorter.

The transmission process is usually quite complex and includes manyoperations such as but not limited to forward correction encoding,interleaving, modulating and the like. A receiver must reverse theprocedures applied by the transmitter.

FIG. 3 illustrates a parent network 5100 and a child network 5200. Eachof these networks is also referred to as a piconet. The parent network5100 includes a first group of ultra wide band devices 5102-5120. Theparent network 5100 includes a management device 5110 that controls theexchange of information between the devices of the parent network, byapplying a time division multiplex access scheme. The child networkincludes a second group of devices 5120 and 5202-5206. Device 5120belongs to both the parent and child networks 5100 and 5200respectively. It controls the exchange of information between thedevices of the second network 5200.

Transmission between devices that belong to the parent network 5100 canbe subjected to interferences from devices of the child network 5200 andvice versa. There is a need to provide an efficient manner for solvingthis interference issue.

SUMMARY OF THE INVENTION

An ultra wide band device that includes: a receiver adapted to receiveinformation from at least one device of a first group of ultra wide banddevices, using a first frequency hopping sequence; and a transmitter,adapted to transmit information to at least one device of the firstgroup of ultra wide band devices, using the first frequency hoppingsequence during at least one time period and further adapted to transmitinformation to at least one device of a second group of ultra wide banddevices, using a second frequency hopping sequence, during at least oneother time period.

A method for ultra wide band transmission, the method includes: (a)allowing a first group of ultra wide band devices to exchangeinformation using a first frequency hopping sequence; and (b) allowingat least one certain device that is responsive to at least onetransmission of information from a device of the first group to exchangeinformation using the first frequency hopping sequence during at leastone time period and allowing devices that belong to the second group toexchange information using a second frequency hopping sequence during atleast one other time period.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood and appreciated more fully fromthe following detailed description taken in conjunction with thedrawings in which:

FIG. 1 is a schematic illustration of two networks (also referred to aspersonal access networks), each including multiple devices thatwirelessly communicate with each other;

FIG. 2 illustrates a typical TDMA frame;

FIGS. 4-5 illustrate a device capable of wireless transmission, and someof its components, according to an embodiment of the invention;

FIG. 6 illustrates a parent network TDMA frame and a neighbor TDMAframe;

FIG. 7 illustrates a parent network TDMA frame and a child TDMA frame;

FIG. 8 illustrates the multiple band groups allocated for ultra wideband transmission;

FIG. 9 illustrates a first frequency hopping sequence;

FIG. 10 illustrates a parent network TDMA frame and an affected networkTDMA frame according to an embodiment of the invention;

FIG. 11 illustrates a first frequency hopping sequence and a secondfrequency hopping sequence, according to an embodiment of the invention;

FIG. 12 illustrates a first frequency hopping sequence and a secondfrequency hopping sequence, according to another embodiment of theinvention;

FIG. 13 is a flow chart of a method for ultra wide band transmission,according to an embodiment of the invention; and

FIG. 14 illustrates a ultra wide band (UWB) device according to anembodiment of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

Some portions of the following description relates to wireless ultrawide band networks that utilize a distributed media access controlscheme. In these networks there is no central media access controller,but rather various devices of the network participate in determining howto share a common wireless medium. It is noted that according to variousembodiments of the invention the disclosed methods and devices can beapplied in networks that utilize a distributed media access controlscheme but differ from ultra wide band wireless networks. It is furthernoted that according to some embodiments of the invention networks otherthan ultra wide band network can apply some of the suggested methods.

Various operations such as transmissions utilize the distributed mediaaccess control scheme in the sense that the access to a shared medium isgoverned by a distributed media access control scheme.

Some embodiments of the invention provide an ultra wide band wirelessmedium access control method and a device capable of performing ultrawide band wireless medium access control schemes.

Conveniently, the device is a part of a ultra wideband wireless networkand has a communication protocol stack that includes at least a PHYlayer and a MAC layer. The MAC layer of such devices controls the accessto ultra wide band wireless medium and is referred to ultra wide bandwireless medium access control.

Examples of devices that have a PHY layer are illustrated in thefollowing U.S. patent applications, all being incorporated herein byreference: U.S. patent application Ser. No. 10/389789 filed on Mar. 102003 and U.S. patent application Ser. No. 10/603,372 filed on Jun. 252003.

The receiver can include various components that are arranged inmultiple layers. A first configuration includes a frame convergencesub-layer, a MAC layer, a PHY layer as well as MAC SAP, PHY SAP, frameconvergence sub-layer SAP and a device management entity can also beutilized. Another configuration is described at FIGS. 4 and 5.

Wisair Inc. of Tel Aviv Israel manufactures a chip set that includes aRadio Frequency PHY layer chip and a Base-Band PHY layer chip. Thesechips can be connected in one end to a RF antenna and on the other handbe connected or may include a MAC layer circuitry.

FIG. 4 illustrates a device 60 that is capable of wireless transmission,according to an embodiment of the invention.

Device 60 includes antenna 61 that is connected to a RF chip 62. RF chip62 is connected to a MAC/PHY layers chip 63 that includes a PHY layerblock 63 and a MAC layer block 64. The MAC/PHY layers chip 63 isconnected to an application entity 66 that provides it with informationto be eventually transmitted (TX) and also provides the application 66with information received (RX) by antenna 61 and processed by PHY andMAC layers blocks 68 and 69 of FIG. 5.

Typically, the MAC layer block 64 controls the PHY layer block using aPHY status and control interface. The MAC and PHY layers exchangeinformation (denoted TX and RX) using PHY-MAC interface 90. The RF chip62 provides to the PHY layer block 63 received information that isconveniently down-converted to base band frequency. The RF chip 62receives from the PHY layer block 63 information to be transmitted aswell as RF control signals. The application 66 is connected to theMAC/PHY layers chip 63 by a high speed I/O interface.

FIG. 5 illustrates various hardware and software components of theMAC/PHY layers chip 63, according to an embodiment of the invention.

The Upper Layer IF block 64 of the MAC/PHY layers chip 63 includeshardware components (collectively denoted 69) and software components(collectively denoted 68). These components include interfaces to thePHY layer (MAC-PHY interface 90) and to the application (or higher layercomponents).

The hardware components 69 include configuration and status registers81, Direct Memory Access controller 82, First In First Out (FIFO) stacks83 and frame validation and filtering components 84, DRP and PCA slotsschedulers 85, ACK processors 86, and MAC-PHY internal interface 87.

The software components 68 include a management module 72, transmitmodule 73, receive module 74 m hardware adaptation layer 75, DMA drivers76, MAC layer management entity (MLME) service access point (SAP) 71,MACS API 70 and the like.

These software and hardware components are capable of performing variousoperations and provide various services such as: providing an interfaceto various layers, filtering and routing of specific application packetssent to MAC data queues or provided by these queues, performinginformation and/or frame processing, and the like.

The routing can be responsive to various parameters such as thedestinations of the packets, the Quality of Service characteristicsassociated with the packets, and the like.

The processing of information along a transmission path may include:forming the MAC packet itself, including MAC header formation,aggregation of packets into a bigger PHY PDU for better efficiency,fragmentation of packets for better error rate performance, PHY rateadaptation, implementation of Acknowledgements policies, and the like.

The processing of information along a reception path may includede-aggregation and/or de-fragmentation of incoming packets,implementation of acknowledgment and the like.

The hardware components are capable of transferring data between MACsoftware queues and MAC hardware (both TX and RX), scheduling of beaconsslots, scheduling of DRP and PCA access slots, validation and filtering(according to destination address) of incoming frames,encryption/decryption operations, low-level acknowledgement processing(both in the TX path and in the RX path),

Device 60 can be a simple device or even a complex device such as butnot limited to a multimedia server that is adapted to transmitinformation frames of different types to multiple devices. It can, forexample transmit Streaming data, like voice, Video, Game applications,etc.) data files during DRP slots, and while PCA slots transmits videoover IP frames, download MP3 files, download MPEG-2 files, and stream ordownload MPEG-4 streams.

Usually, voice frames are associated with higher quality of servicerequirements and accordingly are given higher transmission priorities.The voice frames QoS requirements are followed by video frames that inturn are followed by lower quality of service requirements (lowerpriority transmission) frames such as best effort frames and backgroundframes.

Referring to FIG. 3, in order to prevent such interference the devicesof the child network are allowed to exchange information during one timeperiod, while the devices of the parent network are allowed to exchangeinformation during another time period. Device 5120 that belongs to bothnetworks is able of exchanging information with devices of the parentgroup during the one time period or a portion of that one time period.Typically device 5120 is capable of receiving a beacon frame transmittedby the management device 5110 and accordingly to define the transmissionwindow of the child network.

It is noted that the same inefficient use of the wireless medium canoccur if the child device is replaced by a neighbor network. A neighbornetwork does not include a device that also belongs to the parentnetwork, but the transmissions of devices of the neighbor network mayinterfere with the transmission of devices of the parent network.

FIG. 6 illustrates a parent network TDMA frame 5300 and a neighbor TDMAframe 5400. The parent network TDMA frame 5300 starts by a beacon frame5310 transmitted by the management device 5110. The beacon frame 5310may include information that determines which device can transmit duringvarious time slots of the TDMA frame 5300. The beacon frame 5310 isfollowed by a contention time slot 5312, that is followed by multipleslots CTA_1-CTA_n 5314-5330 that are allocated for a transmission ofdevices from the parent or neighbor networks.

The second slot CTA_2 is allocated for transmissions of devices of theneighbor network. During this time slot the devices of the parentnetwork (except device 5120) are not allowed to transmit. The neighborTDMA frame 5400 includes a neighbor beacon frame 5406 and multiple timeslots (collectively denoted 5402) during which device of the neighbornetwork 5200 are allowed to transmit information. These time slots 5402are followed by a silence period 5404 that starts when CTA_2 of certainparent network TDMA frame 5300 ends and ends when the CTA_2 of the nextparent network TDMA frame 5300 starts.

It is noted that the mentioned above as well as the mentioned below TDMAframes are exemplary and that their content can vary from TDMA frame toTDMA frame.

FIG. 7 illustrates a parent network TDMA frame 5300 and a child TDMAframe 5500. The child network TDMA frame 5500 starts by a child networkbeacon frame 5510 transmitted by device 5210 that acts like a childnetwork management device. The child network beacon frame 5510 mayinclude information that determines which device of the child networkcan transmit during various time slots of the child network TDMA frame5500. The child network beacon frame 5510 is followed by a contentiontime slot 5512, that is followed by multiple slots CCTA_1-CCTA_k5514-5530 that are allocated for a transmission of devices from thechild networks. The last slot CCTA_k 5530 is followed by a silenceperiod.

The second slot CTA_2 is allocated for transmissions of devices of thechild network. During this time slot the devices of the parent network(except device 5120) are not allowed to transmit. The child TDMA frame5500 includes multiple time slots (collectively denoted 5502) duringwhich device of the child network 5200 are allowed to transmitinformation. These time slots 5502 are followed by a silence period 5504that starts when CTA_2 of certain parent network TDMA frame 5300 endsand ends when the CTA_2 of the next parent network TDMA frame 5300starts.

Both child network and neighbor network, as well as other types ofnetworks can be regarded as networks that are affected from thetransmissions of the parent network. These transmissions result in asub-optimal usage of the shared ultra wide band media.

There is a need to provide an efficient method for utilizing the sharedultra wide band media.

FIG. 8 illustrates the multiple band groups 5615-5735 allocated forultra wide band transmission. The first band group 5615 includes thefirst till third bands 5610-5630. The second band group 5645 includesthe fourth till sixth bands 5640-5660. The third band group 5675includes the seventh till ninth bands 5670-5690. The fourth band group5695 includes the tenth till twelfth bands 5700-5720. The fifth bandgroup 5725 includes the thirteenth and the fourteenth bands 5730 and5740. Each band is 528 Mhz wide. The center frequencies of these bandsare: 3432 Mhz, 3960 Mhz, 4488 Mhz, 5016 Mhz, 5544 Mhz, 6072 Mhz, 6600Mhz, 7128 Mhz, 7656 Mhz, 8184 Mhz, 8712 Mhz, 9420 Mhz, 9768 Mhz and10296 Mhz.

An ultra wide band device, such any of devices 5202-5206 or 5102-5120,can perform one out of several pre-defined frequency hopping sequences.Each frequency hopping sequence is limited to frequencies within asingle band group. Each sequence is associated with a unique Timefrequency code. Some codes are allocated for frequency hopping sequenceswhich include a frequency from each band. Other codes are allocated forfixed frequency sequences that include a single frequency.

Before initiating either one of the first or second frequency hoppingsequences the receivers and transmitter that are going to use either ofthese hopping sequence is notified about it. There are various ways toperform such a notification, including sending dedicated messages,synchronization and the like. Conveniently, a transmitter includesinformation representative of the selected sequence within eachinformation frame he sends. Conveniently, each time frequency code isassociated with a unique base time domain sequence and a cover sequencethat belong to a packet/frame synchronization sequence that in turn is apart of an information frame PLCP preamble.

FIG. 9 illustrates a first frequency hopping sequence 6000. Thisfrequency hopping sequence 6000 starts by transmitting a first symbol(represented by box 6002) using a carrier frequency from a first band ofa certain band group (denoted by “band #1”). This transmission isfollowed by a guard period denoted 6004. Guard period 6004 is followedby a transmission of a second symbol (represented by box 6006) using acarrier frequency from a second band of a certain band group (denoted by“band #2”). This transmission is followed by a guard period denoted6008. Guard period 6008 is followed by a transmission of a third symbol(represented by box 6010) using a carrier frequency from a third band ofa certain band group (denoted by “band #3”). This transmission isfollowed by a guard period denoted 6012.

Guard period 6012 is followed by a transmission of a fourth symbol(represented by box 6014) using a carrier frequency from the first band.This transmission is followed by a guard period denoted 6016. Guardperiod 6016 is followed by a transmission of a fifth symbol (representedby box 6018) using a carrier frequency from the second band. Thistransmission is followed by a guard period denoted 6020. Guard period6020 is followed by a transmission of a third symbol (represented by box6022) using a carrier frequency from the third band. This transmissionis followed by a guard period denoted 6024.

An inter-symbol period is defined by the transmission period of thatsymbol plus the guard time that follows this transmission. Each symbolis usually transmitted during a short time period that is convenientlythree hundred nanoseconds long. The guard period is typically aboutsixty nanoseconds long. Thus an inter-symbol period is convenientlythree hundred and sixty nanoseconds.

According to an embodiment of the invention the silence periods arereplaced by periods in which the devices of both networks can operate inparallel, but using different frequency hopping sequences, such as notto interfere with each other.

According to an embodiment of the invention the frequency hoppingsequences can be substantially the same but be time shifted in relationto each other. According to another embodiment of the invention thefirst and second frequency hopping sequences differ from each other andare not just a time shifter version of each other.

FIG. 10 illustrates a parent network TDMA frame 5300′ and a affectednetwork TDMA frame 6100 according to an embodiment of the invention.

The parent network TDMA frame 5300′ does not include a silence period,as the transmission of parent network devices do not interfere thetransmissions of the affected network devices. The affected network, orat least one device of the affected network is adapted to use the firstfrequency hopping sequence during a first period 6102 and use a secondfrequency hopping sequence during a second period 6104. The first periodis used to exchange information with the parent network while the secondperiod 6104 is used for exchanging information between devices of theaffected network without interfering to the devices of the firstnetwork.

FIG. 11 illustrates a first frequency hopping sequence 6000 and a secondfrequency hopping sequence 6100, according to an embodiment of theinvention. The second frequency hopping sequence 6100 equals the firstfrequency sequence but is delayed by an inter-symbol period. The secondfrequency hopping sequence 6100 includes the transmissions of multiplesymbols (denoted 6102-6122) and multiple guard periods (denoted6104-6124).

FIG. 12 illustrates a first frequency hopping sequence 6000 and a secondfrequency hopping sequence 6200, according to another embodiment of theinvention. The second frequency hopping sequence 6200 equals the firstfrequency sequence but is delayed by an half of an inter-symbol period.The second frequency hopping sequence 6200 includes the transmissions ofmultiple symbols (denoted 6202-6222) and multiple guard periods (denoted6204-6224).

It is noted that the previous figures illustrate frequency hoppingsequences that were limited to a single band group that includes threebands. It is noted that the amount of bands per band group, can belarger than three and that the frequency sequence does not necessarilybe limited to frequencies within a single band group.

Those of skill in the art will appreciate that the second frequencyhopping sequence can differ from the first frequency, and not just bebeing a delayed version.

It is noted that at least one device, such as certain device 5120, iscapable of monitoring or controlling the second frequency hoppingsequence to make sure that the transmissions of the second networkdevices do not interfere with the transmissions of the first networkdevices. For example if the frequency hopping sequences differ by acertain delay, that certain device can synchronize to the transmissionsof the first network and then introduce a delay between the frequencyhopping sequences.

FIG. 13 is a flow chart of a method 6500 for ultra wide bandtransmission.

Method 6500 starts by stage 6510 of allowing a first group of ultra wideband devices to exchange information using a first frequency hoppingsequence. Said allowing may include adjusting at least one device of thefirst group to perform such an exchange of information, informing one ormore device that such a frequency hopping scheme should be implemented,and even when it should be implemented.

Stage 6510 is followed by stage 6520 of allowing at least one certaindevice that is responsive to at least one transmission of informationfrom a device of the first group to exchange information using the firstfrequency hopping sequence during at least one time period and allowingdevices that belong to the second group to exchange information using asecond frequency hopping sequence during at least one other time period.

Conveniently, the at least one certain device belongs to the first andsecond groups of devices. Conveniently, the at least one certain deviceonly belongs to the second group of devices.

Conveniently, the second frequency hopping sequence is substantially adelayed first frequency hopping sequence. Conveniently, the first andsecond frequency sequences include hopping between frequencies thatbelong to the same frequency band group. Conveniently, method 6500involves controlling the exchange of information between members of thesecond group by the certain device. Conveniently, method 6500 involvescontrolling the exchange of information between device of the secondgroup by utilizing a distributed media access control scheme.

Conveniently, method 6500 includes transmitting informationrepresentative of the first and second frequency hopping sequences priorto utilizing the first and second frequency hopping sequences.

Conveniently, the first frequency hopping sequence comprises performinga frequency hopping between a transmission of each symbol. Conveniently,the second frequency hopping sequence is substantially a delayed firstfrequency hopping sequence and wherein the delay is a multiple integerof a inter-symbol period. Conveniently, the second frequency hoppingsequence is substantially a delayed first frequency hopping sequence andwherein the delay is fraction of an inter-symbol period.

Conveniently, stages 6510 and 6520 are repeated for allowing arepetition of multiple transmission sessions between members of thefirst network and multiple transmission sessions between members of thesecond network.

Conveniently, method 6500 includes synchronizing between the first andsecond frequency hopping sequences.

Conveniently, the at least one time period comprises a first set of timeperiods and the at least one other time period comprises a second set oftime periods. Conveniently, each time period of the first set isfollowed by a time period of the second set.

It is further noted that FIGS. 3 and 6-14 refer to a network thatincludes a management entity that applies a media access control scheme.It is noted that according to an embodiment of the invention at leastone of the networks can apply a distributed media access control scheme.

FIG. 14 illustrates a device 5555 according to an embodiment of theinvention.

Device 5555 can be substantially similar to device 60 of FIGS. 4-5, orone of the devices of the first and second networks 10 and 20 of eitherFIG. 1 or 26, or be similar to device 5555 of FIG. 39. And can also besubstantially similar to any combination of a receiver and a transmitterillustrated in either one of PCT applications, publication number WO2004/017547A2 and publication number WO 2004/077684A2 of Wisair Ltd.

Device 5555 can include various components that are shared between itsreceiver and transmitter, but this is not necessarily so. It can utilizevarious UWB frequency hopping techniques known in the art.

Device 5555 is capable of exchanging information with ultra wide banddevices that belong to a first group or to a second group of ultra wideband (UWB) devices. The first group of UWB devices can be equivalent tofirst network 10 or to parent network 5100. The second group of UWBdevices can be equivalent to second network 20, to child network 5200 orto an neighbor network (not shown).

In order to exchange information device 5555 includes an UWB transmitter5551 and an UWB receiver 5559. The receiver 5559 is adapted receiveinformation from at least one device of a first group of ultra wide banddevices, using a first frequency hopping sequence. Conveniently, thereceiver 5559 is also adapted to receive information from at least onedevice of the first group of ultra wide band devices, using the firstfrequency hopping sequence during at least one time period and toreceive information from at least one device of a second group of ultrawide band devices, using a second frequency hopping sequence, during atleast one other time period.

The transmitter 5551 is adapted to transmit information to at least onedevice of the first group of ultra wide band devices, using the firstfrequency hopping sequence during at least one time period and furtheradapted to transmit information to at least one device of a second groupof ultra wide band devices, using a second frequency hopping sequence,during at least one other time period. Conveniently, the transmitted isalso adapted to transmit information to at least one device of a firstgroup of ultra wide band devices, using a first frequency hoppingsequence.

The device 5555 can manage the access of device of the first and/orsecond group of UWB devices. Additionally or alternatively, device 5555can also participate in a distributed media access control scheme inorder to control the transmission of devices that belong to the firstand/or second group of devices.

Conveniently, device 5555 belongs to the first and second groups ofdevices. Conveniently, device 5555 only belongs to the second group ofdevices.

Conveniently, the second frequency hopping sequence is substantially adelayed first frequency hopping sequence. Conveniently, the first andsecond frequency sequences include hopping between frequencies thatbelong to the same frequency band group.

Conveniently, device 5555 is further adapted to transmit informationrepresentative of the first and second frequency hopping sequences priorto a utilization of the first and second frequency hopping sequences.

Conveniently, device 5555 is adapted to perform a frequency hoppingbetween a transmission of each symbol. Conveniently, the secondfrequency hopping sequence is substantially a delayed first frequencyhopping sequence and the delay is a multiple integer of a inter-symbolperiod. Conveniently, the second frequency hopping sequence issubstantially a delayed first frequency hopping sequence and wherein thedelay is fraction of an inter-symbol period.

Conveniently, device 5555 is further adapted to synchronize between thefirst and second frequency hopping sequences. Conveniently, the at leastone time period comprises a first set of time periods and the at leastone other time period comprises a second set of time periods.Conveniently, each time period of the first set is followed by a timeperiod of the second set.

According to an embodiment of any of the mentioned above schemes can beapplied by two networks that include at least one relaying device forrelaying information between at least one device of the first networkand at least one device of the second network. By applying the frequencyhopping scheme both networks can operate substantially seamlessly whilethe relaying device can exchange information, during at least one timeperiod, with devices of the first network and exchange information, withdevice of the second network, during at least one other time period.Whereas at least some of the information exchange includes relayinginformation.

It will be apparent to those skilled in the art that the disclosedsubject matter may be modified in numerous ways and may assume manyembodiments other then the preferred form specifically set out anddescribed above. It is noted that each of the mentioned abovecircuitries can be applied by hardware, software, middleware or acombination of the above. The mentioned above methods can be stored in acomputer readable medium, such as but not limited to tapes, disks,diskettes, compact discs, and other optical and/or magnetic medium.

Accordingly, the above disclosed subject matter is to be consideredillustrative and not restrictive, and to the maximum extent allowed bylaw, it is intended by the appended claims to cover all suchmodifications and other embodiments, which fall within the true spiritand scope of the present invention.

The scope of the invention is to be determined by the broadestpermissible interpretation of the following claims and their equivalentsrather then the foregoing detailed description.

1. A method for ultra wide band transmission, the method comprises: (a)allowing a first group of ultra wide band devices to exchangeinformation using a first frequency hopping sequence; and (b) allowingat least one certain device that is responsive to at least onetransmission of information from a device of the first group to exchangeinformation using the first frequency hopping sequence during at leastone time period and allowing devices that belong to the second group toexchange information using a second frequency hopping sequence during atleast one other time period.
 2. The method of claim 1 wherein the atleast one certain device belongs to the first and second groups ofdevices.
 3. The method of claim 1 wherein the at least one certaindevice only belongs to the second group of devices.
 4. The method ofclaim 1 wherein the second frequency hopping sequence is substantially adelayed first frequency hopping sequence.
 5. The method of claim 1wherein the first and second frequency sequences include hopping betweenfrequencies that belong to the same frequency band group.
 6. The methodof claim 1 further comprising controlling the exchange of informationbetween members of the second group by the certain device.
 7. The methodof claim 1 further comprising controlling the exchange of informationbetween members of the second group by utilizing a distributed mediaaccess control scheme.
 8. The method of claim 1 further comprisingtransmitting information representative of the first and secondfrequency hopping sequences prior to utilizing the first and secondfrequency hopping sequences.
 9. The method of claim 1 wherein the firstfrequency hopping sequence comprises performing a frequency hoppingbetween a transmission of each symbol.
 10. The method of claim 9 whereinthe second frequency hopping sequence is substantially a delayed firstfrequency hopping sequence and wherein the delay is a multiple integerof a inter-symbol period.
 11. The method of claim 9 wherein the secondfrequency hopping sequence is substantially a delayed first frequencyhopping sequence and wherein the delay is fraction of an inter-symbolperiod.
 12. The method of claim 9 further comprising repeating stage(b).
 13. The method of claim 9 further comprising synchronizing betweenthe first and second frequency hopping sequences.
 14. The method ofclaim 9 wherein the at least one time period comprises a first set oftime periods and the at least one other time period comprises a secondset of time periods.
 15. The method of claim 14 wherein each time periodof the first set is followed by a time period of the second set.
 16. Anultra wide band device that comprises: a receiver adapted to receiveinformation from at least one device of a first group of ultra wide banddevices, using a first frequency hopping sequence; and a transmitter,adapted to transmit information to at least one device of the firstgroup of ultra wide band devices, using the first frequency hoppingsequence during at least one time period and further adapted to transmitinformation to at least one device of a second group of ultra wide banddevices, using a second frequency hopping sequence, during at least oneother time period.
 17. The device of claim 16 wherein the device belongsto the first and second groups of devices.
 18. The device of claim 16wherein the device only belongs to the second group of devices.
 19. Thedevice of claim 16 wherein the second frequency hopping sequence issubstantially a delayed first frequency hopping sequence.
 20. The deviceof claim 16 wherein the first and second frequency sequences includehopping between frequencies that belong to the same frequency bandgroup.
 21. The device of claim 16 further adapted to control an exchangeof information between devices of the second group.
 22. The device ofclaim 16 further adapted to participate in a distributed media accesscontrol scheme for controlling an exchange of information betweenmembers of the second group.
 23. The device of claim 16 further adaptedto transmit information representative of the first and second frequencyhopping sequences prior to a utilization of the first and secondfrequency hopping sequences.
 24. The device of claim 16 adapted toperform a frequency hopping between a transmission of each symbol. 25.The device of claim 24 wherein the second frequency hopping sequence issubstantially a delayed first frequency hopping sequence and wherein thedelay is a multiple integer of a inter-symbol period.
 26. The device ofclaim 24 wherein the second frequency hopping sequence is substantiallya delayed first frequency hopping sequence and wherein the delay isfraction of an inter-symbol period.
 27. The device of claim 16 furtheradapted to synchronize between the first and second frequency hoppingsequences.
 28. The device of claim 16 wherein the at least one timeperiod comprises a first set of time periods and the at least one othertime period comprises a second set of time periods.
 29. The device ofclaim 16 wherein each time period of the first set is followed by a timeperiod of the second set.
 30. The method of claim 1 further comprisingrelaying information, by a certain device, between a device of the firstgroup and a device of the second group.
 31. The device of claim 16further adapted to relay information between a device of the first groupand a device of the second group.
 32. A computer readable medium havingcode embodied therein for causing an electronic device to perform thestages of: (a) allowing a first group of ultra wide band devices toexchange information using a first frequency hopping sequence; and (b)allowing at least one certain device that is responsive to at least onetransmission of information from a device of the first group to exchangeinformation using the first frequency hopping sequence during at leastone time period and allowing devices that belong to the second group toexchange information using a second frequency hopping sequence during atleast one other time period.